Comb Transducer for Generation of SH0 Mode in Crystalline Piezoelectric Membrane

It is shown that the comb IDT (CT) can efficiently excite SH0 mode in piezoelectric membrane of suitable orientation. The transducer has pitch equal to the wavelength (p=lambda) and the electrode size is half of the wavelength. As compared to conventional IDT, two times higher operation frequency is achieved for the same width of the electrodes. In the case of a membrane, such a transducer has no additional losses related to generation of the bulk waves as it would be in the case of the comb transducer for the SAW on thick substrate. Two geometries are presented: one with solid bottom electrode and one with another comb IDT as the bottom electrode, offset by lambda/2 with respect to the top comb IDT. FEM simulation results are presented for a selected cut of LN.